NATO will forge closer ties with Ukraine and intensify efforts to help build up the country’s military, the alliance’s secretary general said Monday, a day after a controversial referendum in Crimea on secession.

Read about recent developments in the ongoing crisis between Russia, Ukraine and the Crimea region.

KIEV, Ukraine — Apparent Russian snipers drew first blood Tuesday in the three-week standoff over Crimea, killing a Ukrainian soldier when they opened fire on a Ukrainian military center in Simferopol, Crimea’s capital.

The shooting death, the first in what had been a tense, but not deadly, Russian occupation of the Black Sea peninsula, came not long after Russian President Vladimir Putin signed a treaty to annex Crimea, to a standing ovation from his Parliament, and immediately prompted Ukrainian officials to change their rules of engagement, giving their troops the right to use weapons to defend themselves against Russian aggression.

At another Ukrainian military base at the Crimean town of Perevalne, a captain told McClatchy that his force, battle tested in Iraq and Kosovo, finally had received orders from Kiev after three weeks of being surrounded by Russian forces.

“Be brave, stand firm,” he said he’d been told by the interim president of Ukraine, Oleksandr Turchynov, in a phone conversation. “If the Russians spill one drop of Ukrainian blood, the world will be with us.” The captain declined to be identified by name because he fears for the safety of his family.

Details of the shooting were sketchy, with news outlets describing the dead man as an officer in the Ukrainian military’s main mapping and navigation unit, but a Defense Ministry statement described him as a soldier. Another person, whom the Defense Ministry statement described as a captain, was reported seriously wounded.

The Ukrainian News website said that an invading force made up of Russian soldiers and Crimean “self-defense forces” stormed the center about 3 p.m., one hour after Putin’s speech, and told the Ukrainians they were under arrest and took away their papers. When the shooting occurred was unclear.

The shooting death came one day after the United States and Europe imposed what Ukrainians consider laughably weak economic sanctions on a handful of Russian officials in retaliation for Russia’s seizure of Crimea. Ukrainian officials made clear the killing had altered their view of the situation.

“It’s not a political conflict,” said Ukraine’s interim prime minister, Arseniy Yatsenyuk. “It’s a military conflict.”

His words came after Putin and Crimea’s new leader, Sergey Aksyonov, signed the treaty in a ceremony that took place at 2 p.m. in Kiev. The treaty would create not just one but two new republics that would join the Russian Federation. One, of course, would be Crimea. The other would create a new republic out of Sevastopol, the sprawling port city that is home to Russia’s Black Sea Fleet and a favorite retirement spot for former Soviet and Russian military.

In addressing the Russian Parliament and asking it to approve the annexation of Crimea and Sevastopol, Putin spoke widely of the deep and abiding relationship, even affection, between Russia and Ukraine.

At one point he noted the historic links between the two countries: “We are one nation,” he said. “Kiev is the mother of all Russian cities.”

But in Kiev, those words sent a chill through Ukrainians who saw them as a barely disguised threat.

“He means war,” said a Ukrainian woman as she stood in almost the exact center of “the mother of all Russian cities,” not far from what is traditionally viewed as the founding home of the Russian Orthodox Church. Nearby are a series of war memorials for Ukrainians who lost their lives in World War II, Afghanistan and other conflicts.

Declining to be identified beyond her first name, Tatyana, and her age, 63, because she feared becoming a target, she said she believed she spoke for most Ukrainians. “If he thinks we won’t fight for our country, he’s crazy,” she said.

Putin in his speech tried to say that Ukraine had nothing to fear from Russia. “Don’t believe those who try to frighten you with Russia,” he said. “To those who scream that other regions will follow after Crimea, I say we do not want to partition Ukraine. We do not need this.”

But he also noted: “Russia will always protect its interests.”

Paired with frequent Russian government statements, including some that he alluded to during his speech, that the Ukrainian government is run by “fascists from Maidan,” that “Russian speakers are in grave danger” and that Russia has a responsibility to protect ethnic Russians and Russian speakers, many here agreed that his entire speech could be viewed as a threat.

Leading Ukrainian military analyst Oleksiy Melnyk, co-director of Razumkov Center, a research center in Kiev, said it didn’t require much analysis to hear the threat in Putin’s words. He added that clearly the risk of global isolation and the sanctions on Russian officials had not led Putin to back down.

“Every word of peace he spoke was really a word of war,” Melnyk said. “The intent of Western reaction, which is to ensure we don’t see a deepening crisis in Ukraine, is missing the point. The West is now in a state of war with Russia. It’s time they realized it.”

If Putin portrayed Ukraine as a brother nation, his speech also made it clear what country he did not consider a friend: the United States. Relying on rhetoric that recalled the Cold War, he cast the United States as a villainous enemy of Russia, one set on destroying a country dedicated to democracy, personal liberties and fair play.

“Western partners, led by the United States, prefer not to be guided by international law in their practical policies, but by the rule of the gun,” he said, to loud applause. “They have come to believe in their exceptionalism. They believe they are the chosen ones. They believe they can decide the destiny of the world, that it is only them who can be right.”

Putin said that the U.S.-led Western response to recent events in Ukraine had been “rude,” “unprofessional” and “crossed the line.”

“Some Western politicians are already trying to frighten us not only with sanctions but with the prospect of worsening internal problems,” he said, referring to suggestions that Putin might face domestic unrest similar to that which drove Ukrainian President Viktor Yanukovych from power. “We regard such statements as irresponsible and obviously aggressive and will respond appropriately.”

He began his speech by referring to Sunday’s referendum in Crimea as “very democratic.” The official count from the vote in what remains to the West an autonomous region of Ukraine had 97 percent of the region’s eligible residents voting to join Russia. Putin noted a similar percent of Russians, about 92 percent, favored adding Crimea to the federation.

There have been questions raised about the validity of the vote, which officials said attracted about 83 percent of the area’s registered voters overall, though reportedly 123 percent of the registered voters in Sevastopol.

Still, Putin said, through frequent applause, only those with no view of history would devalue the importance of the referendum.

“To understand why, you have to understand the history of what Crimea means to Russia,” he said. “In the hearts and minds of people, Crimea has always been and remains an inseparable part of Russia. This belief, based on truth and justice, was firm and passed from generation to generation.”

Few in Kiev, however, saw anything to agree with in Putin’s presentation. Russia has already invaded and taken control of one region and has an estimated 60,000 troops massing at the nations’ shared border near the Donetsk district of Ukraine.

There’s little talk here of a peaceful resolution.

Vitali Klitschko, a former world heavyweight boxing champion and a leading member of Ukraine’s Parliament, made that clear on Monday when he was asked at a news conference about the Russian threat. He pointedly used the phrase “when the Russians invade,” instead of “if.”